Pipettes and capillary tubes have long been used to collect and dispense fluids. Various types of devices are known for dispensing a volumetric quantity of liquid, such as standard glass and plastic pipettes, serological pipettes, calibrated capillary tubes, conventional medicine or eye droppers, air and positive displacement pipettes and syringes. These devices are, for the most part, inaccurate or expensive to manufacture.
Pipettes generally involve a tube of glass having a narrowed or restricted tip at one end and a soft or flexible bulb assembled onto the opposite end. While the volume of liquid involved in such film or droplets may appear quite small, it is desirable to have pipettes designed to handle quantities measured in micro-liters without introducing unwanted errors.